"Today, we see a way to cure a disease that has been killing children for generations," said Dr. Glenn Green, a pediatric otolaryngologist at the University of Michigan's C.S. Mott Children's Hospital and the senior author of a new report on the boys' cases.

The researchers said that 4D biomaterials could one day help not only patients with respiratory ailments, but also those with disorders involving the heart, bones, muscles or gut.

"The possibilities are really limitless," lead study author Dr. Robert Morrison, a research fellow and resident surgeon at the University of Michigan Health System, told Live Science.

The researchers made the implants using a 3D printer. Three-dimensional printers can create items from a wide variety of materials: plastic, ceramic, glass, metal and even more unusual ingredients such as living cells. The machines work by depositing layers of material, just as ordinary printers lay down ink, except 3D printers can also lay down flat layers on top of each other to build 3D objects.